UHF Band Low Pass Filter
UHF Band Low Pass Filter: What is it?
UHF band is the frequency band from 300MHz to 1GHz. There are many commercial systems in this band such as the GSM band. There are many devices utilizing the unlicensed 315MHz and 433MHz ISM (Industrial Scientific Medical) band such as car remote controls. It is common to find UHF Band Low Pass Filters in such devices and systems.
UHF Band Low Pass Filters are used on both receivers and transmitters
UHF Band Low Pass Filter in Receiver
In receivers, they are used to block out higher frequencies signals from interfering with the receivers. If these signals are allowed to pass through the receivers, they could cause a number of problems like intermodulation distortion or even saturate the receiver.
UHF Band Low Pass filter in Transmitter
In UHF transmitters, UHF Low Pass filters are usually placed after the power amplifier to prevent any harmonics from being accidentally transmitted. The use of UHF Low Pass filter is mandatory in UHF transmitter if the power amplifier operates in saturated mode as the level of the second harmonic will cause the transmitter to fail the radiated emissions requirement set forth by FCC.
| Part Number | 1 dB Cutoff Frequency | Insertion Loss | Rejection | Description |
|---|---|---|---|---|
| ALPF-433M-01 | 433 MHz | 3 dB max | > 50dB @ 800MHz | 433MHz Low Pass Filter, UHF Band LC Filter |
| ALPF-500M-01 | 500 MHz | 3 dB max | >50 dB @ 915 MHz | 500MHz Low Pass Filter, UHF Band LC Filter |
| ALPF-600M-01 | 600 MHz | 3 dB max | > 50 dB @ 1100 MHz | 600MHz Low Pass Filter, UHF Band LC Filter |
| ALPF-700M-01 | 700 MHz | 3 dB max | >50 dB @ 1300 MHz | 700MHz Low Pass Filter, UUHF Band LC Filter |
| ALPF-800M-01 | 800 MHz | 3 dB max | >50 dB @ 1450 MHz | 800MHz Low Pass Filter, UHF Band LC Filter |
| ALPF-900M-01 | 900 MHz | 3 dB max | >50 dB @ 1650 MHz | 900 MHz Low Pass Filter, UHF Band LC Filter |
| ALPF-915M-01 | 915 MHz | 3 dB max | >50 dB at 1700 MHz | 915MHz Low Pass Filter, UHF Band LC Filter |
The Significant Differences between UHF and VHF Band Frequencies
UHF, or Ultra High Frequencies, labels a range of EM (electromagnetic) waves with frequencies that fall between 300MHz and 1GHz, also referred to as the decimeter band or decimeter wave as wavelengths measure from one to ten decimeters. Frequency waves that fall above the UHF band immediately falls to the SHF Band (Super High Frequency) and in the EHF Band (Extremely High Frequency).
Ultra-High Frequency: The Basic Uses
The UHF Band is the widely utilized form of frequency band in everyday usage, like in a UHF Band Low Pass Filter. They transmit television signals and mobile phones also transmit and receive within the UHF region. This frequency band is widely used in public service agencies for two-way communication, usually utilizing a narrowband frequency modulation.
However, it’s been known by many that the UHF Band is being compared to another frequency band in terms of practical applications and in terms of limitations. The frequency band in topic is called the Very High Frequency (VHF) band. For a better comprehension why would these two be compared, read below:
UHF Band Frequencies vs. VHF Band Frequencies
The fact that the UHF band is better than the VHF band is widespread. However, despite UHF offering a lot of advantages, it’s not immediately the best choice, especially now that UHF bands have become more crowded and stayed mired in regulatory unsureness. As a matter of fact, there are a few considerations to consider when choosing between UHF and VHF. These include the following:
- Where and how a system will be utilized
- The number of systems required
- The price, of course
Despite the similar perspectives, UHF systems don’t possess any huge technical benefit over otherwise similar VHF systems. However, interference due to any other electrical equipment is generally lower at UHF frequencies because noise from these external origins becomes less intense as the frequency rises.
In addition, since VHF wavelengths are longer than UHF wavelengths it permits them to travel greater distances and pass through physical obstacles (walls and ceilings), all types of interferences will travel farther, and thus produce more issues, at VHF frequencies. However, in the UHF system, it’s less likely to experience any interference; but, expenses tend to favor the utilization of the VHF system.
UHF Band vs VHF Band: Common Application Issues Encountered
Cost and interference levels are just some of the two matters to consider when choosing between UHF and VHF. However, these application issues may provide more information on both:
Whether the choice would be UHF or VHF, diversity systems is another important requirement. Diversity is especially important for UHF systems because dropouts produced by multipath are more of a problem at UHF frequencies.
If wireless equipment will be utilized in different countries, VHF systems operating on special frequencies in the 169-172MHz range, termed as travelling frequencies, will be a wise economical selection.
Fixed-frequency systems in TV bands may not be the wisest choice when using it for travel. Most channels used in one location or another, and frequency clashes will eventually happen.
Before purchasing VHF or UHF Band Low Pass Filter, one must take better consideration to look at the difference of both the VHF and UHF Band.